“All this means that we may not go back to the old growth path, that potential output may be lower than it was before the crisis.
How much has potential output decreased? It is very hard to tell: we do not see potential output, only actual output. The historical evidence is worrisome, however. The IMF’s forthcoming World Economic Outlook presents evidence from 88 banking crises over the past four decades in a wide range of countries. While there is large variation across countries, the conclusion is that, on average, output does not go back to its old trend path, but remains permanently below it.
The possible good news is that the trend itself appears to be unaffected: on average, crises permanently decrease the level of output, but not its growth rate. So, if past is prologue, the world economy likely will return to its past growth rate. But, especially in advanced countries, the period of above-average growth, characteristic of normal recoveries, may be short-lived or nonexistent. ”